Development of heat pump for drying plastic granules

Frederik Dupond Holdt

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Development of heat pump for drying plastic granules

Project start July 2021. Expected completion date August 2023.

Purpose of project
In Danish industry, approx. 15 % of the energy consumption is used for drying. Therefore, there is a great potential for developing energy efficient drying processes. The purpose of the present project is thus to reduce the large energy consumption in drying processes, as well as to help drive the green transition, where fossil fuels are displaced by electrically driven heating processes.

Plastic production is an example of an energy-intensive process with a great need for both heating and cooling. In this project, we will therefore develop a new drying process with a heat pump for drying plastic granules. 

Project objectives
In many industrial drying processes, a large amount of energy is wasted, which may instead be recovered. Therefore, energy management is an essential part of the drying process, since an efficient energy use will contribute significantly to lowering the overall energy need of the process.

In this project, a process that uses electricity directly for both heating and cooling will be converted to an integrated solution, where the supplied energy – electricity – is minimized by recovering heat from the injection molding machine and by using a heat pump to supply heat at high temperatures up to 90 °C to the plastic granulate dryer.

Heat pumps have great potential as an efficient electricity-based heat supply by recovering excess heat from the process itself. Thereby, the integration of heat pumps for heating the drying air provides a significant increase of the overall energy efficiency, a reduction in electricity consumption and a reduction in CO2 emissions.

The project includes a detailed analysis of the integration process at the production plant of the end-user, representing the plastic industry.

The project is divided into the following phases:

  1. Modelling of heat pump and drying system
  2. Analysis and design of best heat pump solution
  3. Development of a heat pump unit
  4. Testing of Heat pump unit in the lab
  5. Demonstration at the end user
  6. Market potential, future developments and reporting.


  1. DTU Mechanical Engineering (Project Manager – Brian Elmegaard)
  2. Danish Technological Institute
  3. Labotek
  4. Grundfos.

The project is funded by ELFORSK.